With This Prosthetic Belly I Thee Wed
by darthsydious
Summary: Prompt fill for artbylexi and writingwife83 who both requested Sherlock and Molly pretending to be married. Writingwife83 suggested our favorite couple pretend to be married to investigate a string of credit frauds from a birthing clinic. Hilarity, fluff and excitement ensue! Sherlolly and Warstan.
1. Chapter 1

It wasn't often that Sherlock Holmes called upon the aid of Molly Hooper when it came to cases. At least when it came to undercover work.

"I don't understand why John can't assist on this one," Molly said, swinging her shoulder bag down onto the empty chair opposite Sherlock. "He and Mary are back from holiday aren't they?"

"Yes, but I need help of the feminine sort."

"And Mary is unwilling?"

He wrinkled his nose, pursing his lips.

"Oh my God, what did you do?" Molly didn't have to be a genius to know that silence from Sherlock on the subject of Mary Watson meant the Consulting Detective was currently in the dog house.

"I may have dyed Sophia's hair a perfectly harmless shade of purple."

"Purple?!" Molly stared, mouth agape.

"The dye was non-toxic, and it washed out immediately!" Sherlock groused, slouching in his chair. "Sophia said she had her parents' permission, how was I to know?!"

"She is only six," Molly said with a laugh. "Of course she'd want purple hair." Molly knew his attachment to his god-daughter was tremendous. He loved the child dearly, and doted on her. He was known to drop whatever he was doing and rush over if Sophia wanted to see her 'Unca Lock'. Still, one could never be sure what would invoke the wrath of a mother, especially when it came to their children.

"Are you forbidden from babysitting?" She asked quietly after a moment.

"No," Sherlock sighed heavily. "But I am on notice. Right now I think it best to give them a wide berth until things settle down. While the dye does wash out of hair, it does not come so easily off of skin." His mouth twitched as he tried to suppress a grin. "John's hands are as purple as that dreadful Telly Monster on Sesame Street."

Molly covered her mouth, barely stifling her laughter.

"All right," she went to the kitchen, putting the kettle on, still laughing. "Enough said, I've got some vacation time owed me, I'll take a few weeks and help you."

"Thank you, Molly."

She turned, hearing her name. Sherlock had taken to thanking her a good deal more lately. In fact he'd been down right lovely. She turned back to the cupboards, taking down mugs and the sugar bowl, missing Sherlock's fond smile as he watched her putter around the kitchen. He liked seeing her in 221b. He asked her around often, more often to help with experiments in the house than to work on cases. They worked well together, and it was the easiest way for him to relax around her. The more often she came, the more comfortable she was, and vice-versa.

It was not a lie when he'd said he was in hot water with John and Mary. But, when he'd explained the case at first to Mary, she had such a knowing look on her face when she suggested he ask Molly for help instead. Mary had a terribly inconvenient way of knowing what was going on in his head. Between them there was suddenly a silent understanding that, while Mary had already forgiven him for dying Sophia's hair purple, she would pretend to be angry with him for a little while more to give him a reason to ask for Molly's assistance.

"So," Molly's voice broke through his thoughts and he looked up to see her holding out a mug of tea for him. "What's the case?"

He took the proffered cup. "It's at a birthing clinic in Peckham. It seems that over a dozen couples who have attended the classes in the past year have later found fraudulent charges on their credit cards."

"Naturally you suspect foul play from the clinic." Molly said as she slipped her shoes off and curled up on the sofa, tucking her legs underneath her.

"Most definitely," Sherlock nodded (having a very difficult time in not being distracted by how well she fit the corner of the sofa). "I need to get in and investigate. Naturally I will need a cover. Enter, you."

"Me?" Molly laughed. "Well, I suppose I could pretend to be pregnant."

"Just so." With that, Sherlock got to his feet, tea set aside. He disappeared down the hall to his room and went rifling through his wardrobe. "Ah! Here," he came back out, holding aloft the article he was searching for. "I've had this for years, never know when there's a need, shall we try it for size?"

Molly stared at the offending garment. "That's a prosthetic belly."

"Yes. You have to look pregnant Molly. I'd suggest going about it the legitimate way but we really haven't that kind of time."

Molly almost hated herself for turning pink. She grabbed the heavy silicon belly from him, hefting it up and buckling it around her waist.

"This is no good," Sherlock muttered, circling her. "Your boobs are too small."

She turned around, glaring at him, mouth open.

"Sorry! Not- no – _yours_ are fine…but not if you're supposed to be pregnant." Now it was Sherlock's turn to be embarrassed, and Molly laughed at his sudden flustered state.

"I _do_ still posses a few tricks up my sleeves, or rather, cups, in this case," she giggled at her joke, and too the blush that further crept down Sherlock's cheeks to his neck. "I'll make sure I look the part. Now, what is the cover? I'm a single mother-"

"No," he interrupted her, this time crossing the room to the mantle to retrieve a box. "I have to be in the building as well, so a married couple having their first child will be more appropriate."

"Whatever you say," she shrugged. If she was nervous, she did not look it, and just for a moment, Sherlock wished for the days when she might have blushed at the thought of them pretending to be married. The fact that his heart was hammering away in his chest at this moment, at the prospect of people believing she was _his_ wife, that she carried _his_ child said more than enough on his feelings for her. He looked at the box in his hands. Well. One couldn't have everything, and if he could not have Molly's love, he would take her friendship, which was so very dear to him.

"Here," he thrust the box at her, head bowed, looking like a sullen eight year old giving a gift to their schoolyard crush. "Rings." At Molly's gasp he looked up, quickly scanning her features. Had he made a bad choice? Indeed not! She was broadly smiling, yet the flash of pain in her eyes did not go unnoticed by Sherlock. Perhaps she was thinking of her own single-hood.

"These are beautiful, Sherlock, truly," she tugged her ring from the box. "Come on, put it on me," she held it out to him.

Taking the ring from her outstretched hand, he lifted her other in his, slipping the cool metal onto her ring finger. It might have been a very nice moment between the two of them. In fact it _was_ a very nice moment. Here they were in his flat, looking deeply into each others eyes, he'd just slipped an (albeit fake) engagement ring onto her finger. They were literally inches from each other. Sherlock could have kissed her. In fact he was thinking of doing just that when suddenly-

"All right, you git, how the hell do I get this stuff off, you've got a bloody lab under your kitchen sink and I'm not leaving until you help me get this off my hands-" John came blundering in, the moment ruined.

John kicked the door shut, then turned to see Sherlock holding Molly's hand, a large diamond ring on her finger, and Molly carrying what could have possibly been twins. "Oh my GOD what have you done?!" John roared.

"It's a fake!"

"It's for a case!"

Sherlock and Molly spoke at once, then glanced nervously at each other, quickly pulling their hands away at the same time.

"Molly and I are infiltrating a birthing clinic in Peckham," Sherlock explained. "We need a valid excuse to get in. Your hands will remain purple for some time, I recommend wearing gloves when you treat your patients, lest they think you've got something."

"And just how long is this supposed to last?!" John cried, frustrated.

"Probably as long as you keep washing with only soap and water." Sherlock looked at his friend's hands. "Try a solution of rubbing alcohol."

Molly rolled her eyes, smiling sympathetically at John. "Non-gel toothpaste and a nail brush," she said. "Should do the trick."

"Thanks Molly," John nodded. He glanced at Sherlock's retreating form down the hallway before stepping closer to her. "You sure you're okay doing this case?"

"Why? Are you offering to step into my place?" she asked, raising an eyebrow. He pursed his lips, frowning at her.

"I've decided you're spending too much time with Sherlock."

"Actually I've been spending a lot more time with your wife," Molly said with a laugh. "Honestly, I'm fine. I'm looking forward to this, rather!" she had the same smile as when she'd told Greg Lestrade that she was over Sherlock. John didn't believe her this time either.

"Go wash your hands, John," Sherlock called from his room. "Molly and I have work to do!"

John made his way to the door, waving at Molly. "Best of luck to you both," he flashed a grin at Molly. "Let me know how it goes, especially Sherlock in the clinic."

"Oh I'll make sure to call you when it's over," Molly laughed. For once, shared medical knowledge between John and Molly made them both laugh, and heartily. Yes, it would be deliciously funny, seeing Sherlock react to a birthing class. It was just too good an opportunity to pass up.

* * *

 _Authors Note: More than a few of you have messaged me to continue this, and I wanted to let you all know that I had already planned on it! I promise there will be more. Generally, if there isn't a 'complete' tab at the top, I plan on writing more, that's my M.O. I'm glad you all are enjoying the ficlet so much, stay tuned for more!_


	2. Chapter 2

"Nice breathing, ladies, remember short breaths, pant, pant, pant, pant, excellent…"

Up and down the rows of couples, the instructor strolled. Molly lay on her back, knees drawn up, hands on either side of the prosthetic belly, (which was a ghastly, heavy thing) obediently panting, feeling like a bloody dog. She rested against Sherlock's knees, who's hands rested on her shoulders, mindlessly coaxing her along, all the while studying the couples and instructors. Molly did feel guilty, being the only one in the class not suffering under the joys of pregnancy. She kept up the charade by frequent trips to the bathroom, complaining of swollen feet, and aching back. The last complaint wasn't a lie either. The pregnancy belly Sherlock had given her weighed a god-awful two and a quarter stone.

"Did you have to give me such a large belly?" She complained one day. They were heading to a birthing class, and underneath her coat and two layers of clothing, the prosthetic belly was chafing.

Sherlock, to his credit, held the door for her, his free hand on her lower back, helping her keep her balance. "We want it to believable," he shrugged in response.

"Yes but it's killing my back!"

"Oh posh, it isn't as bad as that!" he scoffed, ignoring her death glare. He retrieved his phone from his pocket. "Come on, pre-class selfie."

She looked disbelievingly at him. "What?"

"It's been three weeks, they asked all the couples to promote their classes on Facebook and Instagram." Sherlock explained.

Molly nodded, realizing. "So you made a fake account for us, naturally."

"Naturally. I hope you don't mind I uploaded a few of your pictures from your phone onto it. Just shots of Toby, picture of your new tea mug, that sort of thing. It has to look used."

"No, I guess not," she shrugged then scooted closer as he reversed the camera on his mobile.

He had never had such a time trying not to sound too eager as he told her to scoot closer. It was getting harder these days to keep Molly Hooper in her proper place in his Mind Palace. She trailed after him wherever he went, popping up in the middle of sifting through evidence, usually in some alarmingly revealing nightgown. He blamed the influence of The Woman for that.

With her head against his shoulder, smiling at their reflection, he snapped a shot.

"Bloody hell, what do most people write in these anyway?" he lowered the phone, thumbs hovering over the keys, trying to think of a normal thing couples would say after a birthing class. _'Looking forward to learning about the horrors of after-birth'_? _'Wife loves panting'_? Hm. No. Best not put that one.

"I'll do it," Molly offered. He handed her his mobile and sat back as she quickly tapped out an appropriate tag under the picture before hitting 'share' and giving the phone back to him. She shut her eyes, leaning her head against the seat. The ride to Peckham from Baker Street was almost forty minutes, if the roads were clear. As the day was a bank holiday, there would be plenty of traffic, so Molly settled in for a nap. Two weeks and the case still was not solved, so she had to go back to work. It meant working the case during the day and taking night shifts when she should have been sleeping. Add to this any time they were investigating at the clinic, (which was almost every day) she had to wear the heavy prosthetic belly which pulled uncomfortably at her shoulders and lower back. When she was seated, it pressed against her bladder, and getting out of chairs or off the floor was impossible. She was exhausted, and looked forward to the end of the case, though she would miss seeing so much of Sherlock.

Sherlock let her sleep, knowing she was exhausted. His mobile pinged, alerting him to several people liking the photo Molly had just put up under their fake account. He clicked on it, and was surprised to see that beneath the picture of himself and Molly (a photo he planned on saving, mind) she had typed: ' _Heading to our amazing birthing class today at clinic on west 57_ _th_ _. I have the best hubby!'_ It was followed by several hearts and the full address and name of the clinic.

"Molly why did you write this?"

"Hm?" she cracked an eye open. "What?"

"This? 'Best hubby ever'?"

"I dunno," she shrugged tiredly. "I just wrote what I'd probably write if we were actually pregnant." With that, she shut her eyes again. In her sleep deprived state, she had said precisely what was on her mind (it was a subject, after all, she couldn't help but think about, considering the case).

Sherlock too, had been pondering such a thing, and he suddenly felt the tips of his ears burning at the thought of Molly carrying their child. It didn't embarrass him, rather he thought it might be a nice thing.

"Mind if I camp at your place after class?" she asked suddenly. "I've got work in three hours, I'd just as soon kip it on your couch and take a cab to Barts. Toby has more than enough food in his bowl till the end of my shift."

"There is no need for you to sleep on my sofa. You may have my bed," Sherlock replied. "I've got work to do anyway. I'll wake you in time."

The class that afternoon was all about how to ease the mummy-to-be of her aches and pains, with no small degree of chuckling from the men when full body massage was brought up.

"You wouldn't mind that would you, darling?" Sherlock murmured, not sure if he was more shocked at himself (he tried to convince himself that he was merely playing the part, but even he didn't believe that), or the fact that Molly pressed against him, replying that she'd return the favor in due course. Her smile was positively wicked and teasing, and he had such a distinct feeling she was acting as much as he was in the moment. It was such a marvelous feeling, so comfortable and easy. His arm was around her (as was his habit when they were in class…and on the sidewalk…and sometimes in the cab…) and she was leaning against him. He squeezed her shoulder, pressing a kiss to her forehead, wishing desperately they weren't at a class. She'd think he was only acting, and Sherlock did not want her to think so.

In fact for this entire case it had become a game of 'try and convince Molly it's not an act'. So far, Sherlock was most definitely losing. As soon as they were in a cab and away from the clinic, she'd scoot away from him, as if to give him space.

"You needn't move on my account," he tried, and she only shrugged.

"I know you don't like that sort of thing, and anyway it's just for the case." So he was left alone on his side of the cab. Every day to and from the clinic, he'd remind her she needn't move for him, and every day she'd look embarrassed, and mutter something about him not liking personal contact. He wasn't sure where she got that idea from. In fact he told her so one day, when they returned to Baker Street. She stared at him in disbelief, apparently he'd shocked her.

"You heard me," he said, hands on his hips, looking quite offended.

"Well…isn't it true?" she asked, fidgeting with the buttons on her oversized maternity sweater.

"No! Well…yes, sometimes but I don't mind _you_ touching me…I've never minded, truly."

" _I_ mind."

Her admission was spoken so softly that he almost didn't hear her. At once he could not believe her. Molly Hooper! Molly who had pined for him, and indeed, he'd been almost certain she loved him still, minded touching him?

She seemed to understand his confusion and quickly explained: "It isn't that I mind…truly, it's only…" she lifted her hands only to drop them helplessly again. "It's only a case, Sherlock, and I'm having such a hard time remembering that. If we're to keep being good friends afterwards, I have to remember that this," she motioned between them. "Is all pretend. I can't let myself continue the charade outside the case, because it hurts too much."

Sherlock did not like how terribly sad she looked all of a sudden.

"It's easy, pretending," she continued, softer this time. "It's…lovely and wonderful, because it's _so_ easy and comfortable, you make it so wonderfully simple. But it's just a case. When you solve it, things will go back to the way they were before. I'll be at Barts all day, and you dropping in whenever you need a cadaver or help on a case. There won't be any hand holding or kissing or cheeky double entendres. I love how far we've come from before, that our friendship is on stable ground, that you're comfortable with me. I don't ever want to lose that." Her bittersweet smile turned to a frown, and she blinked to hold back tears. "It hurts too much to let myself hope again. I'm trying not to, because it's not fair to hold you to those hopes, and it's not fair to me either."

All this while, Sherlock had remained silent, letting her have her say. All this while, Sherlock had been thinking.

 _Why in the bloody hell did it have to be just for a case?!_

Apparently, he had not kept that thought to himself, because Molly was suddenly looking at him, confused and somewhat alarmed.

"I- I thought you didn't do relationships," she said finally.

Sherlock rolled his shoulders, shrugging. "I have friends."

"Yes but that's different than being someone's boyfriend."

"I don't want to be someone's boyfriend," his mouth twisted in disgust at the word. "I want to be _your_ …" he paused then, trying to think of the correct word. "Mate…and eventually your husband."

"Husband?" she murmured softly, eyes wide. "You mean…"

"Certainly I do. I meant what I said, why should this just be for a case?" he scrubbed his hand through his hair, frustrated. "I've been trying to tell you for days now, I've solved the case, I just…didn't want to stop pretending. It's ludicrous why we can't stop pretending, and actually have it as our reality. It's what I want, most definitely, the question is, is this what you want?"

"You mean, marriage, children, solving crimes and…cutting up dead people?"

Eyes glittering with anticipation, Sherlock nodded, gentle smile playing upon his lips.

Molly almost lost her voice, scarcely believing this was happening. "Yes that's what I want."

So there they stood, once again facing each other, in fact staring, Molly still wearing the prosthetic belly. Sherlock was fairly certain they were on their way to kissing when the door opened.

Mycroft stood, hand on the knob, brief-case in hand, staring at his little brother and Miss Hooper.

"Oh my God, I was away for too long," he groaned aloud. "What have you _done_ , Sherlock?!"

Molly sniffled loudly, smiling broadly at Sherlock, her eyes brimming with tears. "It's for a case."

Mycroft looked from Sherlock to Molly, open-mouthed, quite horrified. "Little brother, I know you can be hard up for cases but surely you could have called me rather than – oh good lord it's a fake – thank GOD." He sagged into John's chair, dropping his briefcase.

Sherlock, annoyed that the moment between him and Molly was now ruined, swiveled on his heels, facing his brother. "Mycroft. Back from South Korea already? What's it been, a month?"

"Three."

Molly disappeared into the bathroom to unhook the prosthetic belly before returning to make tea.

"Sherlock, what is this all about?" Mycroft asked, low.

"Molly told you, it's for a case," Sherlock replied, watching her move around the kitchen.

"Hmm. And when the case is solved?"

Sherlock shrugged. "Well I can't promise immediate results, naturally, besides I think Molly would like to engage in at least a few months' worth of courting before I propose marriage, and then she'll have to wait until her birth control is out of her system and she of course has to be ovulating-"

Mycroft held up his hand to silence his brother. "Enough. Just tell me when to text mummy the good news."

Sherlock smirked, eyes sparkling mischievously at Molly, who returned her own blushing smile.

"Not to worry, Mycroft. We have every intention of letting mummy know when to fetch her knitting needles and the baby blanket patterns she's been hoarding for years now." Sherlock couldn't help himself. "With any luck, Molly will be in the family way within the year."

Mycroft looked to Molly, flabbergasted, but trying to appear blasé. It was quite a hard pill to swallow, having known Sherlock his entire life. "You're certain you want to be saddled with him forever, Miss Hooper?"

"Of course I am," she smiled, handing him a mug of tea.

He scowled at the mug bearing cats and bumblebees. "Hmm. Yes. I expect you both are. Well my blessing to you both." He glanced at the open bathroom, the fake prosthetic belly hanging off the edge of the door. "I'd keep the details of this case from mummy, at least until you're quite sure you're 'in the family way' as my little brother puts it."

"Just us girls," Molly promised with a laugh, retreating to the kitchen. Sherlock excused himself, following her.

Alone at last, or at least out of Mycroft's line of sight, Sherlock slipped his arms about her waist, pressing a kiss to her cheek. "You're certain?" he asked softly. "I shouldn't like this to feel last minute, or that you think I'm trying to trick you."

"Sherlock, you couldn't trick me, I know you too well. You might fool me for a little while, but I'd catch on soon enough." She smiled up at him, turning to face him. "Let's do as you said before, we'll go out for a couple months, see if this good feeling lasts. I don't expect perfection from you, I don't want you to think you have to become someone you aren't. I love you for who you are. After that, when we're sure, we can go and visit your parents."

He smiled, resting his forehead against hers. "I rather like the way you think, Molly Hooper."

"I thought you would," she rose up on tip-toe, kissing him. "Now go back to Peckham and let them know you've solved the case; I think you've strung them out long enough."

He rolled his eyes. "There's a double meaning in that, and not the cheeky sort," Her sly grin was more than enough of an answer. "Very well. Would you like to come along?"

"No, I'll stay and entertain your brother, I'm sure he'll want to know what's been going on while he was away."

"Right." Another kiss, and he was grabbing his coat and scarf. "I'll be back in a few hours, Lestrade will call if you'll be needed."

"Ta."

She turned back to the living room, about to offer Mycroft another cup of tea when Sherlock returned.  
"I forgot something,"

Before she could ask what, he'd drawn her flush against him, and Molly was more than happy to let him thoroughly snog her. He left her plastered to the door, hair mussed and blushing.

Mycroft rolled his eyes from his chair, slouching lower.

"Sorry," Molly, not quite able to bring herself to be embarrassed, wiped her lips, stumbling to the kitchen. "More tea?"

"If you think you can manage it," Mycroft replied. "Though I think my brother underestimates your impending pregnancy. You'll be lucky if you last the bloody month."

"One can dream," she sighed, refilling his mug.

Happily, this change in her relationship with Sherlock was not a dream, and while it had started out as just for a case, it had ended up being very much their reality.

* * *

 _Stay tuned for a teensy drabble!_


	3. Chapter 3

"Ouch!"

"I told you!" Molly's laughter rang through 221b. A year to the day after the case that had finally brought her and Sherlock together, Molly stood in the living room of their flat, hands on her hips, this time, very much so pregnant for real this time, laughed as she watched Sherlock struggle into the prosthetic belly she once had to wear.

"How in God's name did you do this for three weeks?" He wore the belly over his dressing gown and pajamas, looking positively ridiculous. He winced at the pain of the heavy prosthetic, it pulled uncomfortably on his back and shoulders.

"You're the one who dragged the case out, besides, now I'm doing it for real, and I've still got four months to go!"

"Eugh, it bangs against the bladder every step," he grunted, waddling around the living room.

"You wanted to know what it felt like," Molly shrugged.

"You insisted!"

"Just wanted to share the joys of pregnancy with you, you started this after all."

He smirked at her. "I didn't hear you protesting at the time."

"I didn't at that," she agreed and leaned over, pressing a kiss to his lips.

He rested his hands on either side of the fake belly. "Well this is hardly the reality of pregnancy, I'd imagine the weights are the same, but it doesn't have half the side-affects you suffer with."

"It's to give you an idea-"

"Woohoo, Molly I brought you my back massager, and a couple videos you'd been wanting to borrow-" Mary and John entered 221b. One look at Sherlock, and both Watsons were trying desperately not to laugh.

Sherlock realized he still wore the prosthetic belly, then rolled his eyes, annoyed. "It's for an experiment!"


End file.
